Field of the Invention
Oxide-dispersion-hardened superalloys based on nickel which, owing to their outstanding mechanical properties at high temperatures, are used in the construction of heat engines subjected to high thermal and mechanical loads. Preferred use as bucket materials for gas turbines.
The invention relates to the further development of oxide-dispersion-hardened nickel-base superalloys with overall optimal properties, in particular, in relation to behavior during the secondary recrystallization to achieve a coarse-grain structure and to produce monocrystals of large dimensions.
In particular, it relates to an oxide-dispersion-hardened superalloy based on nickel which is composed of the following main constituents:
______________________________________ Cr = 5-13.95 percent by weight or 14.05-22 percent by weight Al = 2.5-7 percent by weight Mo = 0-2 percent by weight W = 0-15 percent by weight Ta = 0-7 percent by weight Hf = 0-1 percent by weight Ti = 0-3 percent by weight Zr = 0.02-0.2 percent by weight Co = 0-10 percent by weight C = 0-0.2 percent by weight Y.sub.2 O.sub.3 = 1-2 percent by weight Ni = Remainder. ______________________________________
It further relates to a process for extending the temperature range of the secondary recrystallization of an oxide-dispersion-hardened nickel-base superalloy during coarse-grain annealing of a workpiece and during annealing to produce a monocrystal of large dimensions having a cross section of at least 5 cm.sup.2.